Judge O'Malley was appointed to the Bench by President Clinton in 1994. Prior to her appointment, she served as First Assistant Attorney General and Chief of Staff to Ohio Attorney General Lee Fisher from 1992-94. Before joining the Attorney General's office, Judge O'Malley practiced law at Porter, Wright, Morris & Arthur, where she became a partner in the firm's litigation department. Prior to that, she was at Jones Day. Judge O'Malley is currently Case Western Reserve Law School's Distinguished Visiting Jurist, where she teaches patent litigation and regularly serves as a guest lecturer in areas such as trial practice, evidence and criminal procedure.

Kathleen McDonald O'Malley is on the Advisory Board for The Sedona Conference.